Russia conducted a rare missile exercise involving naval vessels and a land-based launcher near islands in its far east that are also claimed by Japan, adding to recent friction between the two nations.

Missiles were launched from a nuclear-powered submarine, a guided-missile cruiser and the Bastion coastal defense system around the Southern Kuril islands, the Russian Pacific Fleet said Thursday, without providing the date of the exercise, according to the Interfax news agency.

The missiles were fired at targets more than 300 kilometers away and hit them, according to the report. The Pacific Fleet didn’t provide a precise location for the exercise, but Russia deployed Bastion coastal defense batteries on Iturup Island, known in Japan as Etorofu, in 2016.

In response to the exercise, Japanese Foreign Minister Toshimitsu Motegi told reporters: “Russia’s military buildup on the four Northern Islands runs counter to Japan’s position and is unacceptable,” according to Kyodo News.

The Southern Kuril islands are controlled by Russia after the Soviet Union seized them from Japan in the final days of World War II. Russian President Vladimir Putin made his first visit to the territory last week when he traveled to Iturup, prompting a protest from Tokyo.

Putin’s visit and the missile test come as Japan has aligned with western nations in support for Ukraine in its defense against Russian invasion, including the imposition of sanctions on Moscow. Tokyo has also supplied nonlethal support for Ukraine’s military, including body armor and transport vehicles.

During his visit to the Far East, Putin said that Japan had recently changed its attitude toward Russia without provocation. He criticized sanctions and said Russia had been described as a major threat in Japanese defense documents.

The dispute over the islands has prevented Moscow and Tokyo from signing a formal World War II peace treaty. While Russia’s possession of the Kurils is “enshrined in international documents,” Moscow was still prepared to seek a solution through a peace treaty with Japan, Putin said last week.

Former Japanese Prime Minister Shinzo Abe sought to reach an agreement with Putin under which two of the islands would be returned to Japan, but since then there’s been little prospect of renewed dialogue. Unlike her immediate predecessors, current Prime Minister Sanae Takaichi has yet to hold talks Ukrainian President Volodymyr Zelenskyy, prompting some speculation that she might try to restart negotiations over the disputed islands with Russia.